Document x5jGER2xXoyJQVwo9rnXKGYkJ
CHEMICAL SAFETY REPORT
PROVIDED AS COMMENTS TO THE PUBLIC CONSULTATION ON THE REACH RESTRICTION PROPOSAL ON PER- AND POLYFLUOROALKYL
SUBSTANCES (PFAS)
Submitted by:
1
Date:
June 29, 2023
Substance:
Polyvinylidene fluoride CAS No.: 24937-79-9 EC No.: 607-458-6
Industrial PVDF-based ultrafiltration membranes required to be installed into (a) new water or wastewater treatment plants designed after EiF (including extensions of/changes to existing plants) subject to special conditions (low spatial requirements) for high quality purification of industrial and urban wastewater, process water and drinking water and (b) existing water or wastewater treatment plants ensuring possibility for maintenance and replacement during the operational life of the plant, both (a) and (b) until at least 15.5 years after EiF.
1 Countries of sales and service:
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Table of Contents
Table of Tables ....................................................................................................3
Table of Figures ...................................................................................................4
Abbreviations ......................................................................................................5
Declaration .........................................................................................................6
1 SCOPE OF THIS REPORT ...............................................................................7
2 PHYSICOCHEMICAL PROPERTIES of PVDF........................................................9
3 LIFECYCLE STAGES OF PVDF AND MEMBRANES RELATED TO
APPLICATIONS
............................................................................................................... 12
3.1 PVDF transportation.............................................................................. 12
3.2 PVDF unloading at casting solution mixing sites ........................................ 13
3.3 Manufacturing...................................................................................... 16
3.3.1 Manufacturing of PVDF UF membranes ............................................ 18
3.3.1.1 Casting solution mixing ............................................................... 18
3.3.1.2 PVDF UF membranes manufacturing ............................................. 19
3.3.2 PVDF UF membranes module production ......................................... 20
3.3.2.1 Sheet making & Drying ............................................................... 20
3.3.2.2 Potting ..................................................................................... 21
3.3.2.3 Testing and finishing .................................................................. 22
3.3.2.4 Cassette assembly ..................................................................... 23
3.4 Service life of the PVDF UF membranes ................................................... 23
3.5 Disposal procedure ............................................................................... 23
4 PFAS EMISSIONS DURING THE LIFE-CYCLE OF THE PVDF UF MEMBRANES......... 24
4.1 Overview of residues/emissions.............................................................. 24
4.2 Manufacturing of PVDF UF membranes .................................................... 24
4.2.1 Workplace exposure ..................................................................... 24
4.2.2 Exhaust air emissions ................................................................... 24
4.2.3 Wastewater emissions .................................................................. 25
4.2.4 Process waste.............................................................................. 26
4.3 Use phase of PVDF UF membranes.......................................................... 28
4.3.1 Background concentrations............................................................ 28
4.3.1.1 PFAS ........................................................................................ 28
4.3.1.2 TOF.......................................................................................... 29
4.3.2 Leaching test for PVDF raw materials (
) ................ 29
4.3.3 Leaching test of newly produced PVDF UF membranes....................... 30
4.3.4 Leaching test for PVDF membranes already in use/installed in water treatment plants........................................................................................ 31
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CHEMICAL SAFETY REPORT 4.3.5 Conclusion on leaching tests .......................................................... 33 4.4 End-of-service life ................................................................................ 34 4.4.1 Incineration................................................................................. 36 4.4.2 Landfilling ................................................................................... 37 5 SUMMARY & CONCLUSION .......................................................................... 40 6 REFERENCES............................................................................................. 44 Annex ............................................................................................................. 46
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Table of Tables
Table 1: Substance identity
9
Table 2: Physicochemical properties of PVDF
10
Table 3: Specific properties of VDF
10
Table 4: Overview on process waste during membrane manufacturing
27
Table 5: Information about PVDF membranes operated in water treatment plants for years 32
Table 6: PVDF tonnages at end of service life based on PVDF commercialized within the
EEA
35
Table 7: PVDF tonnages at end of service life based on PVDF commercialized within the
EEA - optimized
36
Table 8: PVDF tonnages for membrane production and PFAS emissions in 2022
42
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Table of Figures
Figure 1: Structural formula of PVDF.......................................................................9
Figure 2: Transportation system of PVDF raw material consisting of three layers ......... 12
Figure 3: Use of a vacuum lance to transfer PVDF to the storage tank ....................... 13
Figure 4: Overview on Unloading & Mixing Area 1 - Unloading Station ....................... 14
Figure 5: Overview on Unloading & Mixing Area 2 (A) and LEV system connected to unloading system............................................................................................... 15
Figure 6: Filter system and waste collection ........................................................... 16
Figure 7: Main process steps for membrane and module manufacturing ..................... 17
Figure 8: Overview on Unloading & Mixing Area 1 (A) and cleaning room located under Area 1 (B)......................................................................................................... 18
Figure 9: Picture of spin-line at the
production site of
...................... 20
Figure 10: Production of membrane sheets ............................................................ 20
Figure 11: Drying of membrane sheets ................................................................. 21
Figure 12: Potting of membranes to produce modules ............................................. 22
Figure 13: Overview of the testing and finishing room ............................................. 22
Figure 14: Digester filled with 100 g anaerobic inoculum (18 to 25% dry solids) and 20 g of the testing sample. ......................................................................................... 38
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Abbreviations
ACC AoA CSR DU DW ED EU GC/MS HVAC units LC-MS/MS LEV MBR NMP OC(s) PCPs PFAS PFBA PFBS PFHxA PFHxS PFOA PFOS PFPeA PPE PVDF
REACH
RMM(s) RPE SEA SOP SPELC/MS TOF UF VDF
American Chemical Council Analysis of Alternatives Chemical Safety Report Downstream user Drinking water Endocrine disruptor European Union Gas chromatography/mass spectrometry
Heating, ventilation and air conditioning units
Liquid chromatography-tandem mass spectrometry Local exhaust ventilation Membrane bioreactor N-methylpyrrolidone Operational Condition(s) Pesticides, pharmaceuticals, personal care products Per- and polyfluoroalkyl substances Perfluorobutanoic acid Perfluorobutanesulfonic acid Perfluorohexanoic acid Perfluorohexanesulfonic acid Perfluorooctanoic acid Perfluorooctanesulfonic acid Perfluoropentanoic acid Personal protective equipment Poly(vinylidene fluoride) Regulation (EC) No 1907/2006 of the European Parliament and of the Council of 18 December 2006 concerning the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) Risk Minimization Measure(s) Respiratory protective equipment Socio-Economic Analysis Standard Operating Procedure
Solid-phase-extraction liquid chromatography/mass spectrometry
total organo-fluorine Ultrafiltration Vinylidene fluoride
WWTP
Wastewater Treatment Plant
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Declaration
We,
("
"), are aware of the fact that further
evidence might be requested by ECHA to support the information provided in this
document.
Also, we request that the information blanked out in the "public version" of the Chemical Safety Report is not disclosed. We hereby declare that, to the best of our knowledge as of today (June 29, 2023) the information is not publicly available, and, in accordance with the due measures of protection that we have implemented, a member of the public should not be able to obtain access to this information without our consent or that of the third party whose commercial interests are at stake.
Signature:
Date, Place:
General Counsel
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1 SCOPE OF THIS REPORT
uses polyvinylidene fluoride ("PVDF")
to produce ultrafiltration membranes at its
site located in
Importantly, no polymerization process is carried out at the site because
purchases
the PVDF polymer from an EU-based supplier. The
UF membranes manufactured in
the plant in
are sold within the EEA and the rest of the world.
's UF membranes are critical components to industrial-scale water and wastewater treatment plants ("WWTP") owned by municipalities, water companies and industrial companies in the European Union ("EU") and all over the world. UF removes particles, pathogens (parasites, bacteria, and viruses), microplastics and combined with adsorption removes micropollutants (such as pesticides, pharmaceuticals, personal care products ("PCPs"), endocrine disruptors ("EDs")) from liquid media (water). Through this PVDFbased UF, the membranes achieve high quality water purification in the following applications:
Application 1: Production of Industrial Process Water;
Application 2: Production of Municipal Drinking Water;
Application 3: Treatment of Industrial Wastewater;
Application 4: Treatment of Urban Wastewater.
manufactures the following types of PVDF membranes: (together "PVDF Ultrafiltration ("UF")
membranes").
The
site receives
(50 - 500 t) of PVDF raw material per
year, The substance is used for the production of PVDF UF membranes.
Where applicable, the potential of exposure of employees and to the environment to PVDF is highlighted. Measurements and studies analyzing properties relevant for the assessment of emissions and/or exposure to the environment are provided in section 4.
This Chemical Safety Report ("CSR") is part of the
derogation submission from the
PFAS2 Annex XV REACH3 Report ("PFAS REACH Restriction Proposal"). The derogation
submission also consists of an Analysis of Alternatives ("AoA")/Socio-economic analysis
("SEA") provided separately. The aim of this CSR is to provide information on the
substance identity of PVDF, its composition, stability, and degradation (section 2). Most
importantly, this document shall provide information on Risk Minimization Measures
("RMMs") and Operational Conditions ("OCs") of the manufacture, use and disposal of
membranes during their life cycle (section 3). Potential emissions during the life-cycle
stages are outlined. Measurement results and laboratory studies on degradability are used
to support the hypothesis that environmental emissions from the manufacture and use
stages of membranes made of PVDF are minimal (section 4). An overall conclusion based
2 Per- and polyfluoroalkyl substances 3 Regulation (EC) No 1907/2006 of the European Parliament and of the Council of 18 December 2006 concerning the Registration, Evaluation, Authorisation and Restriction of Chemicals
7
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on substance stability, emission sources and measured/laboratory data is provided in section 5.
is also committed to increase the sustainability of the manufacture, application, and disposal of its PVDF-based UF membranes. For this purpose, the company developed a sustainability commitment that will fully apply during the required 15.5-year derogation.
With this information submitted as comments to the public consultation on the PFAS
restriction proposal,
aims to achieve a minimum derogation of 15.5 years (from EiF)
for the manufacturing and placing on the market of PVDF-based UF membranes. By
obtaining a time-bound derogation from the upcoming PFAS Restriction,
ensures
supply for the growing need (urbanization and related population growth, stricter water
quality parameters, climate change, sustainable industry, etc.) of this advanced water and
wastewater treatment technology across the EU and the rest of the world (see chapter 5.1
of AoA/SEA).
considers that its PVDF use is not fully covered by any of the currently
proposed derogations in the PFAS REACH Restriction Proposal. Therefore,
requests
a specific derogation which is described in detail in the AoA/SEA.
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2 PHYSICOCHEMICAL PROPERTIES OF PVDF
PVDF is obtained from
. Its identity is described
in Table 1 and its structure is shown in Figure 1. PVDF homopolymers are polymerized
from vinylidene fluoride ("VDF", 1,1-difluoroethylene) either via a suspension or an
emulsion process to control for the melting temperature and crystallinity ratio targeted for
the specific products (
).
Table 1: Substance identity
EC number
607-458-6
CAS number
24937-79-9
Chemical name
Ethene, 1,1-difluoro-, homopolymer
Other names
Poly(vinylidene fluoride) (PVDF)
Molecular formula
-(C2H2F2)n-
Figure 1: Structural formula of PVDF
has a purity of > 99.9% (
). The
impurity content is < 0.1%.
(
), and is described as a very high molecular weight PVDF homopolymer in powder
form (
). Physicochemical properties of PVDF are
summarized below in Table 2.
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Table 2: Physicochemical properties of PVDF
Property Physical state Melting/freezing point
Density
Vapour pressure Partition coefficient noctanol/water (log value) Water solubility
Description of key information solid 170-175 C 1.7-1.8 g/cm (bulk density: 0.5-1 g/cm) not applicable
not applicable
insoluble
Source
As indicated above, the base material for the PVDF material is the monomer VDF. VDF has
a very low boiling point of - 83C (NCBI, 2023), and it is readily volatilized (and captured
or destroyed) during polymer manufacture processing and drying steps (Korzeniowski et
al., 2023). Furthermore, the residual VDF monomer concentration in PVDF has been
reported as < 50 ppb (Korzeniowski et al., 2023); this is in line the reported purity of PVDF
used for the production of membranes, which has a concentration of > 99.9 % (
). In total
of PVDF have been received by the
membrane manufacturing plant in 2022. Considering an assumed monomer
content of < 50 ppb (see above) a total amount of < g VDF/year may be expected as
residues in the manufacturing plant.
Table 3: Specific properties of VDF
Property
Description of key information
VDF boiling point:
-83C
Water solubility
Insoluble; 164.9 mg/L (at 25C)
Partition coefficient
log Kow = 1.24
VDF monomer content in PVDF
< 50 ppb
1) Data directly extracted from NCBI, a secondary source of literature
Source NCBI (2023) 1)
NCBI (2023) 1)
NCBI (2023) 1) Korzeniowski et al.
The use of fluorinated processing aids in the PVDF raw material is highlighted in a letter (April, 2022) from the manufacturer as follows:
"[...] To the best of our knowledge concerning relevant raw materials and manufacturing processes,
is produced without any intentional use and/or addition of (Per- and polyfluoroalkyl substances, PFAS) fluorinated process aids including PFOA (Perfluorooctanoic acid), its salts and PFOA-related compounds. However given the
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ubiquitous nature of PFAS, the presence of unintentional impurities of these substances could exist. [...]" 4
The communication is attached in Annex 3.
Reactions resulting in the generation of VDF monomers during membrane mixing solution
preparation are considered to be excluded based on physicochemical behavior of the
polymer. According to the manufacturer's information, PVDF shows a high chemical
stability against most inorganic acids and salts, organic acids, alcohols, ethers, aliphatic
and aromatic hydrocarbons (
). It is furthermore resistant
against crude oil and fuels, as well as halogens (except fluorine) (
). A more detailed overview on substances, concentrations and associated
maximum temperatures may be found in the referenced document. Dimethylformamide,
dimethylsulphoxide and N-methylpyrrolidone ("NMP") are listed as classic polymer
solvents (
); as described later, NMP is also used by
during membrane manufacturing.
PVDF may also be subject to chemical attack from free radicals and bases
). As outlined by Rabuni et al. (2013) and Marshall et al. (2021) mild or
strong (pH 11) basic conditions, respectively, may lead to degradation of PVDF.
However, expert knowledge and experience of
shows that membranes last years
under typical working conditions in drinking water and wastewater plants. Degradation as
described above would lead to loss of polymer properties, loss of mechanical membrane
integrity and would result in membrane failure, which is monitored frequently during
operation. Such deterioration process, even if not so intense, would be well monitorable
by the membrane integrity decline and also by the brownish discoloration of the membrane
fibers in the modules which is not the case and is never reported. Membranes are thus
stable under typical conditions in areas of intended application.
In general, PVDF is stable to a temperature of ~ 400C (cf. section 4.4.1); therefore, no thermal degradation is considered in the areas of actual application of PVDF UF membranes (~ 0- 40C). As no thermal degradation is assumed, no generation of VDF or other PFAS by-products is expected either from manufacturing or during the subsequent uses of the membranes.
Further information on stability of PVDF can be found in section 4.4, where details on incineration and anaerobic biodegradation are given. The Safety Data Sheet of
can be found in Annex 4.
4 "PFOA", Perfluorooctanoic acid
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3 LIFECYCLE STAGES OF PVDF AND MEMBRANES RELATED TO APPLICATIONS
3.1 PVDF transportation
PVDF is delivered to the
site in
~ 30 times per year. In total, the site
received
of PVDF in 2022. The PVDF raw material is received in a three-layered
transportation system. Two outer layers made of polyethylene shrink wrap and an octabin
cardboard box provide structural stability to the packaging system and protect the content
from moisture. Importantly, environmental contaminants are effectively prevented by the
packaging system.
The raw material PVDF is located in a super sac/big bag made of polypropylene within the octabin cardboard box. The big bag is not porous, preventing emissions from dust, and keeping the raw material, and surroundings uncontaminated. The big bag is also directly used for further unloading tasks. Example pictures are provided below.
Figure 2: Transportation system of PVDF raw material consisting of three layers
Panel A) displays shrink-wrap packaged octabin container, panel B) shows the big bag after removal of shrinkwrap within the cardboard box, panel C) indicates the unloading procedure required for mixing processes in Unloading & Mixing Area 2.
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The unloading part of the Unloading & Mixing Area 1 has no specific Local Exhaust Ventilation ("LEV") or other air extraction system in place, and no exhaust air emissions are emitted from this process location. To reduce worker exposure to process chemicals as well as PVDF as dust, employees conducting the task wear nitrile gloves (EN 374-1), a disposable protective lab coat (EN 1149-1), and respiratory protective equipment ("RPE") in form of a full-face respirator (EN 136) with a particle (EN 143 P2) or combined filter (EN 14387 ABEK2P3). Worn personal protective equipment ("PPE") is visible in the overview of Unloading & Mixing Area 1 (Figure 4).
It is worth noting that the average particle diameter of
was analyzed
as 112.2 to 119.7 m in a study conducted for
in 2022. Smaller particles (1st decile)
were identified as 68.7 to 70.5 m, with larger particles (9th decile) in the range of 163.0
to 182.9 m. According to a publication by the European Commission Joint Research
Center (2002) particles with an aerodynamic diameter of > 100 m "are not included in
the inhalable convention", while particles with an aerodynamic diameter of 10 m are
counted towards the thoracic fraction; smaller particles (aerodynamic parameter of 4 m)
are considered respirable. While the reported particle size of
relates
to the measured diameter, and not the aerodynamic diameter, a direct comparison is not
possible. However, as the average density of PVDF homopolymer is 1.78 g/cm and PVDF
is reported to consist in most cases of spherulites (phase ) (
), the data might serve as an indicator that the respirable or even inhalable fraction
of PVDF dust is low.
Used PPE and packaging materials are disposed as hazardous waste under European Waste Code 150110*, as contaminated packaging material, and 150202* as contaminated PPE.
Figure 4: Overview on Unloading & Mixing Area 1 - Unloading Station
During the task the employee wears adequate RPE. However, due to reasons of data protection this section of the image has been redacted.
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In the second unloading and mixing area (internally termed MMP mixing area) 56 % of the PVDF raw material is processed. In this area, Big Bags are brought in every days. big bags are completely unloaded during these occasions, there is no temporary storage in the area. A batch used for production of membranes is
.
The octabin containing the PVDF in a big bag is transported to the loading position using a pallet-jack.
The big bag is removed from the octabin using a crane (Figure 5 - Panel A). The bottom of the big bag is connected to the loading system inlet. The contents of the big bag are transferred to a storage silo in a closed dust
conveyor system. A LEV is connected to the unloading point (Figure 5 - Panel B). On demand, PVDF is transferred to the scale tank, and subsequently loaded into a
selected mixing tank.
Figure 5: Overview on Unloading & Mixing Area 2 (A) and LEV system connected to unloading system
During the task the employee wears adequate RPE. However, due to reasons of data protection this section of the image has been redacted.
Used PPE and packaging materials are disposed of under the waste codes described above.
With regard to the LEV, air is filtered to capture PVDF and other organic dust. However,
no air is emitted to the environment. An F7 type bag filter (previous EN 779 standard) is
used. This filter has an efficiency of 80 to 90% of filtering dust with particle sizes of 0.4
m. While no direct conversion to the new ISO 16890 standard is possible, it is considered
by
technical experts that the closest category that fits the parameters above is ePM1
60%.
PVDF and other organic dust ingredients trapped in the auxiliary exhaust filter is regularly
emptied and disposed as hazardous waste (16 05 08*). Waste extracted from the filter
system is collected in a polyethylene ("PE") bag via a dedicated valve (Figure 6). This
process is conducted ~ 1 per year. An estimated amount of <
% of filtered waste
(PVDF and other organic dust) is collected and disposed annually.
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The filter itself is cleaned automatically in a closed system via air scouring using compressed air. During this process, the dust particles collected by the filter are dislodged and collected in the PE bag underneath.
Figure 6: Filter system and waste collection
3.3 Manufacturing
PVDF UF membranes manufactured in the
manufacturing plant are hollow fiber
and may be manufactured either with or without an internal support structure. The
support, if used, is a polyester woven, hollow format structure called braid. Braids are
used for required stability and flexibility. The manufacture of braid supports has not been
considered in this CSR, as the process does not contain PVDF, and is conducted before
PVDF is introduced into the process. Depending on product type and support required,
manufactured membrane fibers are formulated into sheets or bundles before being
assembled into modules and cassettes. An overview on the production process is given in
Figure 7. The process steps are explained in more detail in the following sub-sections.
Tasks related to the manufacturing of filtration membranes, as well as, module production are conducted continuously on a daily basis.
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(EN 143 P2) or combined filter (EN 14387 ABEK2P3). Contaminated PPE is treated as hazardous waste during all process steps (including the unloading of PVDF) and is shipped off for incineration. Work clothes worn underneath disposable Tyvek suits or lab coats are not disposed of but cleaned by the company they are leased from.
3.3.1.2 PVDF UF membranes manufacturing
Membranes are produced on spin-lines. Several spin-lines are installed to produce the
range of products manufactured in the
site.
The membrane casting solution mixture is pumped through a special annular die into a
coagulation bath of
where the final hollow membrane is formed. In the coagulation
NMP solvent is exchanged with water, in which only soluble components will dissolve; the
membrane forming polymer will not dissolve, but precipitate, thereby generating the
porous coagulated polymer membrane structure. The hollow tubular form of the
membrane is realized by either using a support braid material (see section 3.3) or via use
of a bore fluid of different composition (e.g.,
).
All spin-line baths for coagulation and rinsing are equipped with local air exhausts connected to point source emission points. These serve mainly for the emission control of NMP. Amongst the measured substances each air emission point source is subject to a permit which requires the plant to conduct air measurements every 5 years, or if there is a change in technology.
Results are submitted to the regional environmental agency for approval. There are no further emission sources in this area. Fresh air for the spin-line areas (which are located in a large open process hall) is provided by central HVAC units.
Wastewater from the tanks is directed to the factory industrial WWTP for treatment. Wastewater is passed through a membrane bioreactor ("MBR") with PVDF UF membranes. Additional info on wastewater are presented in section 4.2.3.
Membranes and remnants of casting solution mixture which are not fully coagulated are handled as hazardous waste under code 06 10 02. Scrap membrane is generated for example when the composition of the membrane mixture is changed and the spin-line has been re-started; it is determined by several quality parameters if membranes are considered scrap material (e.g., incorrect diameters). Scrap membranes that have undergone full coagulation are handled as non-hazardous waste under code 07 03 13.
The end-part of a spin-line i.e., where the freshly-made membrane fiber is collected on spools is shown in Figure 9.
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There are no point source air emissions in this process step. Scrap modules (rare) are handled as non-hazardous waste under code 07 03 13. The wastewater (glycerine, sodium hypochlorite water) generated in this area is directed to the industrial WWTP for treatment.
3.3.2.4 Cassette assembly
In the final production step, membrane modules are assembled into cassette frames. As a first step, the cassette frame is assembled, and the integrity of the permeate system of the cassette frame is tested. After loading of modules (e.g., 52 modules as the most common cassette setup) into the frame, the integrity of the cassette is tested (dry PDT).
After assembly and passing of QC requirements, the cassette is packed and prepared for delivery in crates.
3.4 Service life of the PVDF UF membranes
The standard service life of a membrane is ~ 10-20 years. No PVDF emissions from the
membranes are expected during the service life. To support the hypothesis that PVDF
membranes are stable and environmental exposure of PVDF by the use of membranes is
small,
commissioned leaching tests on aged membrane material. The results are
described in section 4.3.4 below.
For a detailed description of the service life of AoA/SEA.
membranes, please refer to the
3.5 Disposal procedure
At EOL, PVDF UF membrane modules are disposed of by customers through incineration
(hazardous/non-hazardous) or landfills (hazardous / non-hazardous).
has
conducted a survey amongst its DUs. Based on the responses (n = 14 DUs) it was
concluded that 45 % (n = 4) of used PVDF UF membranes are landfilled and 55 % (n = 5)
are incinerated, 5 DUs did not provide answers (not reaching end-of-life yet). Recycling is
not considered in this assessment.
As indicated previously,
has commissioned studies to further examine the potential
for releases from incineration and anaerobic biodegradability. The results are displayed in
sections 4.4.1 and 4.4.2. It is furthermore highlighted that, as part of this comment,
commits to complete an ongoing feasibility study on the recycling of EOL membranes and
study and develop guidelines on the disposal of used membranes via incineration.
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4 PFAS EMISSIONS DURING THE LIFE-CYCLE OF THE PVDF UF MEMBRANES
4.1 Overview of residues/emissions
Potential PFAS emissions have been investigated for all relevant life stages (manufacturing, use phase and end-of-life phase).
Manufacturing: PFAS leaching from raw material has been tested and also different sources for emissions have been investigated for PFAS/PVDF residues (e.g., dust, wastewater and other waste articles).
Use phase: PVDF membranes with different `service times' have been investigated for PFAS leachates.
End-of-life phase: Disposal to incinerators have been discussed and anaerobic degradation (representing disposal to landfill) have been tested for PVDF breakdown/stability.
Overall, no breakdown of PVDF (except incineration) could be observed and also no relevant PFAS concentrations were detected or are to be expected during the different life stages of PVDF.
4.2 Manufacturing of PVDF UF membranes
4.2.1 Workplace exposure
The PVDF is transferred in "unloading areas" where a filter system is installed with a filter
mesh size of F7 according to old EN 779 standard (means efficiency 80-90% of filtering
particle size of 0.4 m). This is equivalent to the new ISO 16890 standard "ePM1 60%".
Considering the implemented filter system, it is highly unlikely for PVDF particles to pass
the filter system, as its 1st decile particle size is 69.5 m according to
internal data
and is thus larger than the filter particle size by a factor of 173.
Workplace exposure to PVDF may mainly occur at Unloading Areas 1 & 2:
In Unloading Area 1 any PVDF powder spilled or PVDF dust accumulated in the zone is swept / vacuumed then sent to hazardous waste incineration.
Unloading Area 2 has an LEV system for the collection of dust; dust is transferred to a PE bag. Collected dust is disposed of as hazardous waste. Dust from filter cleaning is also collected in a PE bag and disposed of as hazardous waste. Any PVDF powder spilled or PVDF dust accumulated in the zone is swept / vacuumed then sent to hazardous waste incineration.
Less than
% of the total PVDF/year used for membrane production in
membrane manufacturing plant is emitted as dust. This is equivalent to < kg PVDF when
considering the tonnage used for PVDF manufacturing in 2022 (i.e.
).
4.2.2 Exhaust air emissions
Based on the process description outlined above, no emissions of PVDF to exhaust air are expected. Main sources for potential contaminations and emissions are areas in which
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PVDF raw material is handled, before it is dissolved for the membrane casting process. A LEV system is installed in Unloading & Mixing Area 2. However, PVDF dust extracted with this system is not emitted into the environment but filtered and collected. It thus primarily serves to control workplace exposure towards PVDF in dust form. In Unloading & Mixing Area 1 no LEV is installed. In later process steps (after dissolving PVDF) LEV systems are mainly installed to control for solvent exposure.
Based on physical / chemical properties of PVDF polymer as well as the process structure no PVDF is expected to be emitted via air/vapor exhaustion.
(1) When PVDF is introduced and thus the solution
viscosity is relatively high, reducing the chance that PVDF in any form would be emitted via NMP vapours.
(2) During the dosing of PVDF there is no vacuum applied in the
kg level
(Unloading Area 1) casting solution mixing which minimizes the chance for PVDF
powder to leave the mixer.
(3) During the dosing of PVDF there is vacuum applied in the
kg level
(Unloading Area 2) casting solution mixing, but the vacuum is used to pull PVDF
powder into the solution from below the solution level into an already elevated
viscosity solution which minimizes the chance to have PVDF powder escaping from
the solution through the vacuum system
(4) Even if there is certain NMP vapour pressure measurable in the gas phase in the closed mixer kept under reduced pressure during mixing, the chance that dissolved PVDF molecules would be co-evaporating from the liquid into the gas phase is considered extremely low due to the very high molecular weight of the polymer and logically assumably low vapour pressure of the solid material even in dissolved state.
In addition to these arguments,
is nonetheless committed to investigate analytical
means / methodology to detect PVDF in air.
4.2.3 Wastewater emissions
For PVDF membrane production, about 1000 to 1300 m3 industrial wastewater per day (not combined with flushing toilets, showers, etc.) are emitted from spin-line operation,
, cooling water for mixing and used reverse osmosis water from testing tanks. Before the wastewater enters the municipal sewer system, it is purified/treated at various stations (Equalization Tank 1: coarse screen, Equalization Tank 2: Pre-treatment - drum screen 1 mm, MBR and sludge treatment/dewatering for land application).
It is assumed that no PVDF is emitted by industrial process wastewater as PVDF is insoluble in water and it is not considered to be able to pass in any form (solubilized or suspended) through the membrane bioreactor (MBR) with ultrafiltration membrane (pore size about 10 to 50 nm).
Water samples were taken at different stages of water treatment and were screened for
PFAS compounds (see Annex 5) in 2021 and 2022 by two laboratories using liquid
chromatography-tandem mass spectrometry ("LC-MS/MS") following EPA 533 and
internal method GLS OC 400:2021-04-15, respectively (
and Eurofins Wessling
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.). No relevant5 PFAS concentrations above the reporting limit (1.0 ng/L in report; 17 to 65 ng/L in Eurofins report) were identified.
In addition, wastewater samples were taken at different stages of water treatment and analyzed by a contracted laboratory using gas chromatography-mass spectrometry ("GC/MS") for residues of organic fluorine compounds (e.g. CHF2+, CF3+, C2HF3+ or C3HF6+). However, concentrations above the detection limit of 0.15 mg/L were not found indicating that PVDF does not degrade during manufacturing.
Analyzed PFAS and organic fluorine compounds were below analytical detection limits in
wastewater samples and thus none of the analyzed PFAS is expected in the sludge
produced by the WWTP.
is however committed to analyze the sludge for
completeness in this series of analysis.
Please note however that raw material leaching tests identified TOF values above the detection limit. Due to the production process small amounts of leached TOF may thus end up in wastewater and sewage sludge (see section 4.3.2).
4.2.4 Process waste
Different waste articles could occur during the PVDF membrane manufacturing process e.g., filters, scrapped membrane casting solution, and scrapped membranes. This waste can contain PVDF and are either incinerated or disposed of in landfills. It was estimated that during production around % of ordered PVDF are discarded as process waste. Quantities of PVDF waste for different production steps are presented in Table 4.
Please note that the waste treatment is considered similar for process waste and waste occurring at the end of the membrane service life. Waste treatment is described in section 4.4.
5 In the
report, the lab blank and field blank samples indicate a PFBA contamination of approx. ~2 ng/L.
Concentrations up to 6.4 ng/L were detected and are considered background concentrations not related to PVDF
membrane manufacturing. Moreover, PFPeA has been identified above the reporting limit in the field reagent
blank (1.1 ng/L) and in few wastewater samples up to concentrations of 2.3 ng/L.
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Table 4: Overview on process waste during membrane manufacturing
Waste name/origin Waste description
EU waste code/labelling
Final destination
Waste/year
% PVDF in waste
PVDF in total waste/year
Organic chemical waste e.g., dust from raw material PVDF
16 05 08
Organic chemical waste (hazardous waste)
Hazardous incineration
2019:
kg
2020:
kg
2021:
kg
2022:
kg
% 1)
2019: kg 2020: kg 2021: kg 2022: kg
PVDF Packaging3) & PPE / unloading zone
PVDF powder plastic liner packaging & PPE
07 02 13
Non-hazardous Plastic waste
Hazardous incineration
<
kg
< % 1)
< kg
Scrapped membrane Liquid membrane
06 10 02
Hazardous
2019:
t
%1)
casting solution/ membrane manufacturing
coating material
Hazardous Chemical Preparation Waste
incineration
2020:
t
2021:
t
2022:
t
2019: t 2020: t 2021: t 2022: t
Scrapped membranes / Coated ( %) and
07 02 13
Non-hazardous
2019:
t
%1)
membrane manufacturing
uncoated ( %) membranes. % Dry / % wet
Non-hazardous Plastic waste
landfill
2020:
t
2021:
t
membranes 2)
2022:
t
2019: t 2020: t 2021: t 2022: t
1) Indicative 2) Dry & wet membranes refer to glycerinated & non-glycerinated membranes 3) PVDF powder cardboard packaging is not included in the table as it is recycled. No contamination with PVDF for the cardboard packaging is expected as a "super sac" is used which is a physical barrier to block any contamination from outside in and PVDF from inside out. The "super sac" is a non-porous material that blocks gases and dust to pass through.
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4.3 Use phase of PVDF UF membranes
PVDF UF membranes have been rigorously tested and meet drinking water standards throughout the world. Certifications include NSF 61, NSF 419, KTW (Germany), KIWA (Netherlands), ACS (France), DWI (UK), ICIM (Italy), Hungary, Poland, Czech, MOH (China), KWWA (Korea). Information on potential PFAS release during the use of PVDF membranes for drinking water treatment can be derived from these certificates. NSF 61 (NSF/ANSI/CAN Standard 61) certification requires the assessment of Hexafluoropropene and VDF release. Other certifications, like ACS in France, impose very strict requirements including testing for "unexpected organic substances".
In addition to these certificates, a set of leaching tests were performed to investigate potential release of PFAS and total organo-fluorine ("TOF") from PVDF membranes focusing on the following life-cycle stages of PVDF:
Raw materials
used by
for membrane production;
Newly produced (pristine) PVDF membranes;
PVDF membranes already in use/installed in water/WWTP for some years.
PFAS analyses were conducted by
North American R&D Analytical Laboratory based
in
, USA. TOF analyses were conducted in the laboratories of Bureau Veritas
(Canada).
It is also important to mention that during the use phase of PVDF UF membranes, the
performance of the membranes and as a consequence, the integrity of the membranes, is
continuously controlled and monitored through turbidity measurement and other relevant
water quality parameters. In addition, for Municipal Drinking Water application, a
membrane integrity test is automatically performed on a daily basis. Integrity failures are
caused by upstream failures causing damage to the downstream membranes (e.g., debris
entering the treatment system). Failures are not caused by polymer material degradation.
This has been found to be the case in every autopsy completed by
when following
up on integrity failures at customer plants.
4.3.1 Background concentrations
4.3.1.1 PFAS
As certain background concentrations of different PFAS compounds can be found in the environment, it is important to consider these background contaminations for the analysis. In order to account for these background concentrations, laboratory equipment and chemicals were analyzed and showed the following results:
The chemicals used for PFAS determination by the analytical laboratory contained 2 ng/L perfluorobutanoic acid ("PFBA") and 2-3ng/L perfluorooctanesulfonic acid ("PFOS") above detection limit. These values for PFBA and PFOS were considered as analytical background for all PFAS measurements performed and thus, the 2 ng/L PFBA and 2-3 ng/L PFOS background values were subtracted from the
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measured PFBA and PFOS concentration values while concentration values of other PFAS compounds were used as reported.
MilliQ ultrapure water used in all experiments was measured to contain no PFAS above the detection limit for all samples (considering analytical background PFBA and PFOS levels).
Hypochlorite solution used in all experiments was measured to contain <3.6 ng/L PFBA and no other PFAS compounds above the detection limit (considering analytical background PFBA and PFOS levels).
Hotmelt and UV glue was measured to contain low levels (1.6 ng/L) of PFBA and brought only this PFAS compound to the membrane leaching experiments which was considered within background.
Membrane filtration equipment was measured to add no PFAS compounds to the water-based membrane leaching experiments above detection limit.
Plastic packaging used for the used membrane samples from sites did not release PFAS above the detection limit.
Plastic beakers and cylinders were measured to bring ~6 ng/L PFBA to the PVDF raw material leaching experiments.
Filtration glassware were measured to bring ~4 ng/L PFBA to the PVDF raw material leaching experiments.
Nitrile gloves were measured to bring 4 ng/L PFBA and 2 ng/L PFOS to the PVDF raw material leaching experiments.
Determination of PFAS detection limit
The instrumental detection limits for the measured PFAS are 1 ng/l. As stated above, the chemicals used for PFAS determination by the analytical laboratory contained 2 ng/L PFBA and 2-3 ng/L PFOS and therefore these values were subtracted from the measured PFBA and PFOS concentrations while concentrations of other PFAS compounds were used as reported.
4.3.1.2 TOF
Sampling of laboratory equipment did not result in TOF concentrations above the detection limit (1 g/L).
4.3.2 Leaching test for PVDF raw materials (
)
Method
In order to find any PFAS by-products and TOF within the PVDF raw material, 10 g of PVDF powder (raw material) was inserted in a glass filter packed in between two paper filter sheets. For the PFAS analysis, water (50 mL) was driven through the material and the process was repeated 10x times and finally diluted to 130 mL, which was collected in the sample vial. For TOF, the same method was used, but the raw material was extracted in 390 ml of water without further dilution.
The
laboratory applied the EPA 533 (solid phase extraction and LC-MS/MS)
method to monitor 25 PFAS compounds in aqueous matrices with reporting limits of 1 ng/L
(ppt). The entire 125 mL sample is loaded onto an anion exchange cartridge to capture
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PFAS compounds and then eluted to generate a concentrated extract for liquid chromatography mass spectrometry analysis (LC-MS/MS).
TOF analysis performed by the Laboratory of Bureau Veritas (Canada) used a combustion
ion chromatograph following method
(
).
The limit of detection is 1.0 g/L.
Result
Water-leached PVDF
raw material (10 g PVDF extracted with 50 mL water
(10x), diluted to 130 mL) does not release any PFAS above the analytical detection limit
(1 ng/L) or background levels. However, the measured TOF concentration was 8.7 g/L in
one sample. Of the analysed PFAS, no substance was measured at this level; this suggests
an impurity of a different organo-fluorine compound within the raw material. It is however
considered unlikely that the gaseous VDF is the source of the TOF as it would likely
evaporate from the sample.
Based on the mass of the sample and extraction volume (10 g raw material in 390 ml), a
TOF amount of 339.3 g/kg can be calculated. In relation to an annual tonnage of
t
of PVDF, a TOF mass of g/a may be expected within the
manufacturing plant.
The TOF leaching from raw material may end up in the spinline wastewater and
subsequently in the wastewater treatment MBR as no TOF was found to be leaching from
newly produced membranes (see section 4.3.3). Although the emissions do not originate
from
itself but from the raw material used for membrane production,
will
carry out further investigations to understand the nature of this potential g/a emission
and its fate.
4.3.3 Leaching test of newly produced PVDF UF membranes
Method
Pristine (newly produced, unused) membrane samples from the final filtration membrane
product have been used to investigate potential PFAS and TOF release. Samples were
taken from `the
Membrane Manufacturing Plant'. Two types of pristine
membranes were used in this study:
1.
membrane;
2.
membrane.
Both membrane types were received from the production plant in glycerol-wetted condition. Before use in the tests both membrane types have undergone the typical deglyceration process (water-soaking for 24 h at room temperature) which is also used in the field at water treatment sites.
The membrane fibers were then formulated into 50 cm long closed loops and glued into a T-connector with hot glue and connected to the peristaltic pump of the filtration apparatus.
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The membrane loop (50 cm) was used to permeate 600 mL water through the membrane
recirculating the permeate using outside-in permeation mode for 48 h, 2 mL/min flow rate,
40 lmh (L/mh) flux at room temperature. In 48 h the fluid volume (
: 0.1 mL,
: 0.4 mL) in the membrane lumen recirculated 57 600 times in the
and 14
400 times in the
membranes. In 48 h the total solution volume (600 mL) was
recirculated 9.6 times. At the end of the run a 130 mL permeate sample of the 600 mL
was collected and sent for PFAS/TOF analysis.
For PFAS analyses, samples were investigated by the
Laboratory following the
EPA 533 (solid phase extraction and LC-MS/MS) method to monitor 25 PFAS compounds
in aqueous matrices with reporting limits of 1 ng/L (ppt).
The laboratory of Bureau Veritas (Canada) used a combustion ion chromatograph following
method
to determine TOF in the samples. The limit of detection is 1 g/L.
Result
The de-glyceration process (water-permeation, 24 h) of newly produced
and
membranes does not release PFAS above the detection limit or background
concentrations of the measurement.
48 h water leached sample of newly produced
releases PFBA and PFOS within the
range of background levels of the laboratory equipment/chemicals (see 4.2 for
consideration of PFAS background contaminations).
48 h water leaching of newly produced and de-glycerated
and
membranes
does not release PFAS above the detection limit or background concentrations of the
measurement.
48 h water leached samples of newly produced no TOF above detection limit (1 g/L).
and
membranes release
4.3.4 Leaching test for PVDF membranes already in use/installed in water treatment plants
Method
Used membrane samples have been taken from different water treatment plants with different applications and operational time to determine potential PFAS residues within the membrane.
All membrane samples were harvested from different membrane modules of the actual
plant and have been closed at both ends of the membrane fiber to avoid foulants to enter
the lumen (permeate) side of the membrane. The membrane samples were packed in
plastic bag and sent to
(
Membrane Development
Lab).
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Table 5: Information about PVDF membranes operated in water treatment plants for years
Location WWTP Plant in Italy WWTP Plant in Italy WWTP Plant in Finland DW Plant in Italy DW Plant in Germany DW Plant in Germany DW: Drinking water
Application Urban MBR Urban MBR Urban MBR Municipal DW Municipal DW Municipal DW
Module configuration 340-sq ft 250-sq ft 370-sq ft 440-sqft 370 sq ft 370 sq ft
Age 11-year-old membranes 6-year-old membranes 4-year-old membranes 7-year-old membranes 11-year-old membranes 20-year-old membranes
Pieces of clean bags were sampled for PFAS analysis for reference of packaging material. The fouled membrane fiber pieces were pre-cleaned with hypochlorite solution (1000 ppm) using inside-out permeation (30s/600s: 20 lmh/relaxation cycles) for 48 h and the permeated membranes were rinsed with ultrapure water after this sanitization and foulantremoving process. Alternatively, some used membrane fibers were not pre-cleaned and were used as is.
The membrane fibers were then formulated into 50 cm long closed loops and glued into a T-connector with hot glue and connected to the peristaltic pump of the filtration apparatus.
The membrane loop (50 cm) was used to permeate 600 mL water or 1000 ppm
hypochlorite solution through the membrane recirculating the permeate using outside-in
permeation mode for 48 h, 2 mL/min flow rate, 40 lmh (L/mh) flux at room temperature.
In 48 h the fluid volume (
0.1 mL,
0.4 mL) in the membrane lumen
recirculated 57 600 times in the
and 14 400 times in the
membranes. In
48 h the total solution volume (600 mL) was recirculated 9.6 times. At the end of the run
a 130 mL permeate sample of the 600 mL was collected and sent for PFAS analysis.
The
laboratory used the EPA 533 (solid phase extraction and LC-MS/MS) method
to monitor 25 PFAS compounds in aqueous matrices with reporting limits of 1 ng/L (ppt).
The entire 130 mL sample is loaded onto an anion exchange cartridge to capture PFAS
compounds and then eluted to generate a concentrated extract for liquid chromatography
mass spectrometry analysis (LC-MS/MS).
TOF analysis was analyzed by the Laboratory of Bureau Veritas (Canada) using a
combustion ion chromatograph following method
. The limit of detection
is 1.0 g/L.
Results
48 h water leaching of all tested drinking and wastewater application membranes do not release PFAS above the analytical detection limit and taking laboratory PFAS contamination background levels into account. Foulant removed from used membranes by water rinsing showed the highest concentration of PFAS and also the highest variety of PFAS. Analysis
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of the foulant material showed concentrations about ~1-10 ng/L PFBA and ~1-7 ng/L PFOS, ~1-10 ng/L perfluorobutanesulfonic acid ("PFBS"), ~1-4 ng/L perfluorohexanoic acid ("PFHxA"), ~1-2 ng/L PFOA and ~1-10 ng/L perfluoropentanoic acid ("PFPeA") (including potential background concentrations). The PFAS measured in the foulant on the membrane surface likely originated from the water/wastewater treated by the PVDF membranes.
48 h water leached samples of used above the detection limit.
and
membranes released no TOF
4.3.5 Conclusion on leaching tests
Tests described in previous sections were conducted to answer the questions outlined in bold font. Brief summaries of the main results are reported below:
Does the raw material
used by
for
membrane production contain/leach out PFAS compounds?
PFAS analysis after water-based leaching showed no PFAS compounds higher than the limit of detection or background levels released from
raw material.
Does the raw material
contain/leach out organic
compounds which can be measured by TOF?
raw material does contain measurable (8.7 g/L) organic fluorinated compounds which can be considered as contaminants.
Do newly produced PVDF UF membranes leach out PFAS compounds?
and
membranes do not release PFAS compounds via water-
filtration above analytical detection limit or analytical background levels caused by
the laboratory equipment. Typical field-related preparatory de-glyceration process
(water-based rinsing) does not release PFAS compounds above analytical detection
limit or laboratory background levels.
Do newly produced PVDF UF membranes contain/leach out fluorinated organic compounds which can be measured by TOF?
and
membranes do not release organic fluorinated compounds
above detection limit (1.0 g/L).
Do PVDF UF membranes already in use/installed in water treatment plants leach out PFAS compounds?
PVDF UF membranes operated in wastewater and drinking water filtration applications up to 20 years from 6 different field examples were shown not to release PFAS compounds by water leaching above analytical detection limit when considering laboratory background concentrations. In one case, PFBS was measured in concentrations above the detection limit; however, this analyte might be attributed to PFBS from remaining foulant as related foulant samples showed higher concentrations of this substance.
Do PVDF UF membranes already in use/installed in water treatment plants contain/leach out fluorinated organic compounds which can be measured by TOF?
PVDF UF membranes operated in wastewater and drinking water filtration applications do not release organic fluorinated compounds above the detection limit (1.0 g/L).
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4.4 End-of-service life
The estimation of annual waste resulting from the end of service life is based on the volume
of PVDF ordered by the manufacturing site in
In 2022, the site ordered ~
t
of PVDF. It was estimated that during production around % of ordered PVDF are
discarded as process waste (cf. section 3.5 and4.2), being a sum of % disposed to
landfills and % disposed to incineration.
The remaining
t of PVDF are considered to be commercialized as membranes modules,
of which % are commercialized within the EEA. Consequently, a waste tonnage of t
of PVDF membrane modules is expected to be disposed as waste at the end of their service
life.
As indicated in section 3.5, a DU survey was conducted by
. Of the total number of
14 DUs, five DUs did not provide an answer to the question on waste disposal (membranes
not reaching end of life); four DUs reported that modules are disposed to landfills (45 %),
and five DUs reported that modules are incinerated (55 %). As outlined in the AoA/SEA,
strives to support the transition from landfilling to incineration of their DUs.
Accordingly, it is estimated that from 2027 onwards no service life waste is landfilled.
Please note that
currently works on a process optimization to reduce raw materials
consumption (see details in section 5.5.2. of the AoA/SEA).
PVDF waste based on commercialized PVDF from 2007 until 2040 according to the current situation, as well as, the optimized raw materials use scenario are presented in Table 6 and Table 7, respectively.
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Table 6: PVDF tonnages at end of service life based on PVDF commercialized within the EEA
Year
PVDF ordered (t)
PVDF commercialized within EEA (t)
End of service life (10 years) reached in year
EEA waste based on commercialized PVDF (t)1)
Landfill (nonhazardous or hazardous)
Incineration (municipal or hazardous)
2007
2017
2008
2018
2009
2019
2010
2020
2011
2021
2012
2022
2013
2023
2014
2024
2015
2025
2016
2026
2017
2027
2018
2028
2019
2029
2020
2030
2021
2031
2022
2032
2023
2033
2024
2034
2025
2035
2026
2036
2027
2037
2028
2038
2029
2039
2030
2040
2031
2041
2032
2042
2033
2043
2034
2044
2035
2045
2036
2046
2037
2047
2038
2048
2039
2049
2040
2050
1) About 45% of commercialized PVDF within the EEA is disposed of in non-hazardous landfill and about 55% is
disposed of via incineration in accordance to an downstream users ("DU") survey.
2)
strives to support the transition from landfilling to incineration of their DUs; accordingly, it is estimated
that from 2027 onwards no service life waste is landfilled
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Table 7: PVDF tonnages at end of service life based on PVDF commercialized within the EEA - optimized
Year
PVDF ordered (t)
PVDF commercialized within EEA (t)
End of service life (10 years) reached in year
EEA waste based on commercialized PVDF (t)1)
Landfill (nonhazardous or hazardous)
Incineration (municipal or hazardous)
2023
2033
2024
2034
2025
2035
2026
2036
2027
2037
2028
2038
2029
2039
2030
2040
2031
2041
2032
2042
2033
2043
2034
2044
2035
2045
2036
2046
2037
2047
2038
2048
2039
2049
2040
2050
1) Including 50% PVDF recycling plan
2)
strives to support the transition from landfilling to incineration of their DUs; accordingly, it is estimated
that from 2027 onwards no service life waste is landfilled
4.4.1 Incineration
With regard to thermal degradation of PVDF, for example, Silva et al. (2020) reported that
PVDF has a thermal stability but starts degrading in higher temperatures. The authors
present that PVDF degradation occurs in two processes: (i) from 400 to 510 C, and (ii)
from 510 to 700C. The majority of the polymer mass was reported to be lost in the first
phase. A thermal stability up to 375-400C was also indicated by
for the
product
. A comparable thermal stability of PVDF containing photovoltaic
backsheets has been demonstrated by Danz et al. (2019).
Moreover, Silva et al. (2020) summarize two competitive routes of thermal degradation of PVDF, leading to the formation of e.g., hydrogen fluoride and diene species, which subsequently will result in aromatization of macromolecules, or e.g., to halogenated/oxygenated compounds, VDF monomer and hydrogen fluoride. Similarly, Danz et al. (2019) indicate that "most of the fluorine was released into the gas phase during pyrolysis and incineration". However, the generation of reaction products is expected following data published in literature (here: referred to fluorinated photovoltaic backsheets) (Danz et al., 2019). In a publication by Aleksandrov et al. (2019) on the incineration of PTFE - which is structurally similar to PVDF - it was reported that the substance does mainly transform to fluorine as hydrofluoric acid. It was also concluded by
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the authors that PFAS identified in the incineration stream are likely related to contaminations.
Based on the information summarized above, the formation of complex reaction products cannot be excluded during waste treatment via incineration. Overall, this image is reflected in the Annex B to the PFAS Annex XV REACH Report (ECHA et al., 2023), and it is stated that "most publications conclude [...] that most sampled PFASs are destroyed >99%". It is however highlighted in the Annex XV Report, that a discrepancy between laboratory and field data may exist, due to unacknowledging operational variations, and also PFAS may be used in the incinerator for pollution control, making it difficult to assess the actual emissions from an incinerator (ECHA et al., 2023).
Municipal incinerators have been described to operate at a temperature of 850C, while hazardous waste incinerators may reach higher temperatures (ECHA et al., 2023). It was therefore considered in Annex XV Report, that releases from incineration stations during waste treatment cannot be excluded. However, no estimation of releases from the incineration of waste has been derived as part of this report as no reliable degradation and/or release rates were identified for PVDF. It was considered not applicable to model emissions using default factors published, e.g. those published in the ECHA guidance on waste (ECHA, 2012), as it remains to be clarified if these are in the range of actual emission rates.
It should furthermore be noted that
has also commissioned a study to examine
emissions of PVDF and (the formation of) by-products. Results of this study are expected
before end of 2023. In addition,
is in contact with the American Chemical Council
("ACC") to collaborate on a program to carry out pilot scale tests followed by an industrial
scale trial. Beyond
proposed R&D activities on PVDF incineration, we understand
that comments related to PFAS incineration will be provided by Hazardous Waste Europe
(HWE) and other stakeholders during the public consultation.
4.4.2 Landfilling
As PVDF is non soluble in water and stable under common environmental conditions, it
can be considered to be not bioavailable. To provide more information about potential
degradation under landfill conditions,
has carried out an anaerobic biodegradability
study in accordance with ASTM D5511 (a standard test method for determining anaerobic
biodegradation of plastic materials). This study should confirm the stability of PVDF in
landfills.
It is acknowledged though that landfilling conditions are not uniform. A possible solution to give more insights into disposal via landfill could be achieved by considering modelling results. However, due to the variety of environmental conditions in landfills, modelling of releases from landfills is difficult. In addition, no PVDF specific data/release rates were identified that may serve as indicators for the potential of releases to leachate. Consequently, it was not considered feasible to reliably estimate emissions from landfills via modelling due to the weak database.
Method ASTM D5511 test
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The objective of this test is to determine whether PFAS are formed as a result of PVDF
membrane biodegradation under simulated landfill disposal conditions. The ASTM D5511
test is conducted at 52C and chopped
membrane, pure PVDF powder, a positive
control (cellulose) and blank negative controls were tested. As an inoculum anaerobic
digestate from urban
WWTP (Illinois, USA) was used. The different
samples were incubated within the digesters for 60 days. Then samples were taken to
determine potential degradation to PFAS in water and solids.
After the main study was concluded, supernatant of the membrane, PVDF powder and
positive control vessels were sent to the
laboratory in
After removal of
solids by centrifugation and decanting, the prepared supernatant was tested for PFAS
(see Annex 7) following EPA method 533 and the analysis was conducted using Solid-
Phase-Extraction-LC/MS ("SPE-LC-MS"). The reporting limits ranged from ~ 1-2 ng/L. A
second control group (inoculum only) as well as a field blank were sampled at test start.
Moreover, solids samples were drawn and analyzed in the laboratories by Bureau Veritas towards 22 PFAS compounds (see Annex 7) at test end. They were analyzed using SPELC-MS, following method ASTM D7968-17a m. The detection limit was 1 g/kg dry solids. Samples had to be pooled due to small sample volume in individual replicates. A second control group (inoculum only) as well as a field blank were sampled at test start. The detection limit was 20 g/kg for these samples.
Figure 14: Digester filled with 100 g anaerobic inoculum (18 to 25% dry solids) and 20 g of the testing sample.
Results
After 60 days of incubation, the anaerobic biodegradation study resulted in biodegradation rates of 5.9 % (membranes) and 1.6 % (PVDF powder) (measured as Theoretical amount of CO2 (ThCO2 equivalent) via production of CO2 and CH4). The positive control (cellulose) showed 84.8 % ThCO2 equivalent. Initial and final pH were 8.2 and 8.5, respectively, throughout test and control samples. As specified in the report, the biodegradation rates
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of membranes and PVDF powder are so small that they cannot be interpreted as a sign of biological degradation.
Supernatant analysis revealed PFAS in negative control and test samples. In samples of membranes and PVDF powder, 3 and 8 PFAS compounds, respectively, were measured in concentrations above the detection limit. In contrast, the negative controls (blanks, inoculum only) had 12 PFAS compounds in concentrations above the reporting limit (it is common to find PFAS traces in urban sludge). The summed, averaged concentration of all PFAS measured ranged from < 79.5 ng/L in the membrane sample, < 153 ng/L in the PVDF powder sample, and < 253.1 ng/L in the negative control. Furthermore, while the highest concentration of PFBA showed up in the PVDF powder sample (29 ng/L versus 18 ng/L and 19 ng/L in PVDF powder samples and negative control, respectively), the remaining highest concentrations of individual PFAS were found in the negative control. For example, PFOA was found in concentrations of 36 ng/L in the negative control, 17 ng/L in the PVDF powder sample and was below the reporting limit in the membrane sample. Similarly, PFOS was identified in the negative control in concentrations of 56 ng/L but did not exceed the analytical detection limit in both membrane and PVDF powder samples. Data from the initial control and field blank sampled at test start revealed distinctly lower levels of PFAS; five and two PFAS compounds, respectively, were identified in concentrations with highest concentrations of 11 ng/L PFOS in the inoculum blank.
Solids samples from the membranes and PVDF raw material groups analyzed at test end detected just a single PFAS compound above the detection limit each (14 ng/L PFOS and 1.4 ng/L perfluorohexanesulfonic acid ("PFHxS"), respectively). By contrast, in the negative control, five PFAS were found in concentrations above the detection limit; the highest concentration was 8.5 ng/L PFOS. Moreover, the initial negative control sampled at test start contained 22 ng/L PFOS. PFHxS was not identified in negative controls. Overall, the membrane and PVDF powder groups did not exhibit higher levels of PFAS than the controls - results were within the variability and background levels observed for the control.
In summary, reported degradation rates under anaerobic conditions were so small (< 6 %) that they cannot be interpreted as a sign of biological degradation. Analysis of supernatant of test media (membranes and PVDF powder) showed that PFAS can be detected in concentrations above the reporting limit. While PFAS were found in supernatant of both membrane or PVDF powder samples, the control sample showed comparable or even higher values of PFAS. Also, the number of identified PFAS compounds was higher for control samples. Analysis of solids revealed similar results.
The ASTM D5511 test, despite its aggressive conditions, did not demonstrate biodegradation of the membrane or PVDF raw material. In addition, PFAS levels in supernatant controls are comparably high and do not allow the conclusion that membranes and raw material contributed to the measured PFAS levels. The test did show evidence that PVDF is stable in landfill conditions.
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5 SUMMARY & CONCLUSION
Within this CSR, the different life stages of PVDF membranes were identified: manufacturing, operation, and end-of-life. The sources of potential PFAS emissions to the environment at each stage were identified, as were RMMs. A summary is also provided in tabular form below (Table 8).
PVDF is purchased from
It is polymerized exclusively from 1,1-difluoroethylene
(VDF), not involving other per- and polyfluoroalkyl substances. In 2022, a total of
tons of PVDF were used at the
site for the manufacturing of PVDF membranes.
For the manufacturing stage of PVDF membranes, potential emission sources for
PFAS/PVDF include dust, wastewater, and other waste articles. Of the tonnage used, less
than
% hence less than kg of PVDF, were emitted as dust in areas where PVDF
raw material is handled. To capture these emissions, one unloading area is swept or
vacuumed in case of any incidental spills and the other unloading area is equipped with a
filter system. Additionally, these two areas are regularly cleaned. The waste from cleaning
is collected and disposed of as hazardous waste. Contaminated water coming from the
removal of incidental spills of PVDF raw material is disposed of and sent for incineration.
In the process steps after PVDF was dissolved, exhaust ventilation systems are installed.
The concentration of residual monomer (VDF) in PVDF was determined to be < 50 ppb
(Korzeniowski et al., 2023) and therefore considered to be of limited relevance for further
environmental assessments of PVDF used for membrane manufacturing. The leaching of
PFAS by-products from PVDF raw material into water was examined, and no PFAS
concentrations above analytical detection limits were identified. Moreover, the leaching
potential of PVDF raw material was examined by TOF analysis. The results indicated low
concentrations (ng/L), resulting in a potentially leachable amount of g TOF/a in relation
to the annual tonnage of
t (2022). The TOF leaching from raw material may end up
in the spinline wastewater and subsequently in the on-site
MBR wastewater
treatment plant as no TOF was found to be leaching from newly produced membranes (see
section 4.3.3).
will carry out further investigations to understand the nature of this
potential g TOF/a emission and their fate.
During the production of PVDF membranes, around 1,000 to 1,300 m of industrial wastewater are emitted per day, which is directed to the on-site MBR wastewater treatment plant before entering a municipal wastewater treatment plant. Wastewater samples confirmed that no typically measured PFAS or TOF were found in concentrations above analytical detection limits. It is assumed that also no PVDF is emitted by industrial process wastewater as PVDF is not considered to be able to pass in any form (solubilized or suspended) through the MBR with ultrafiltration membrane (pore size about 10 to 50 nm). Finally, any other waste produced during the manufacture of PVDF membranes, such as organic chemical waste, PVDF packaging or scrap membranes, is either incinerated or disposed of in landfills for non-hazardous waste. The exact amounts per waste type can be found in section 4.2.4. Since analyzed PFAS and organic fluorine compounds in wastewater samples were below analytical detection limits, it can be assumed that none of the analyzed PFAS is expected in the sludge produced by the WWTP. Nonetheless, is also committed to further investigate this matter.
The next stage in the lifecycle of PVDF membranes is their service life. PVDF raw material, freshly produced membranes, and PVDF membranes operated in water technology process for years (4-20 years) have been tested for PFAS and TOF emissions. No PFAS releases
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above analytical detection limit and/or including analytical background were detected in membrane leachates. Foulants removed from used membranes contained some PFAS above the background levels. However, as these foulants are considered to accumulate PFAS from different sources during the use phase these measurements are interpreted as independent from PVDF membranes. This also relates to a measurement of leachate of a cleaned membrane, which showed concentrations of PFBS above the limit of detection. The correlated concentration of PFBS in the foulant as well as the leachate of the uncleaned membrane were considerably high and indicate a remaining contamination. Leachate of cleaned, used membranes from the other five scenarios did not result in PFBS values above the detection limit.
The last stage concerns the end-of-life phase of PVDF membranes, which is currently
handled by incineration or disposal in landfills for non-hazardous waste. In a survey,
downstream users (DUs) were asked about their methods of disposing of the
UF
membranes. Different methods such as non-hazardous landfill (29 %), municipal
incineration (14 %) and hazardous waste incineration (21 %) emerged. Regarding
incineration, it is concluded that no estimations of PFAS/PVDF releases from the
incineration of waste can be made, due to the lack of reliable degradation and/or release
rates for PVDF. Moreover,
has commissioned a study on this topic, and results are
expected before the end of 2023.
Concerning the disposal to landfills, an anaerobic biodegradability study on PVDF
breakdown/stability has been conducted on behalf of
The calculated biodegradation
rate is so small that it cannot be interpreted as biological degradation. In addition, PFAS
levels in the supernatant and solids of control groups were higher than or comparable to
the range of values detected for the membrane and PVDF powder groups. The overall
study shows evidence that PVDF is stable in landfill conditions.
From the data summarized above it was concluded that the emission potential during the life cycle of PVDF-membranes is extremely low and controlled. The emissions to the environment from the manufacturing process are considered to be controlled due to the implemented RMMs and the technical prerequisites of the process. Data on waste treatment (especially incineration) are currently being created; furthermore, new data suggest that the potential for creation and emission of PFAS from PVDF incineration is limited.
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Table 8: PVDF tonnages for membrane production and PFAS emissions in 2022
PVDF Life-cycle step
Manufacturing Total PVDF ordered for PVDF membrane manufacture Produced PVDF membranes
Estimated PVDF waste during manufacturing
Estimated PVDF in wastewater or sewage sludge (applied in land application)
Leaching from operational PVDF membranes
Tonnage PVDF (in 2022)
~ t
Percentage of total ordered PVDF in 2022
Disposal route
100 %
PFAS emission?
~
t
~ t
~ % of total PVDF amount per year
~ % of total PVDF amount per year
t
% of
total amount per
year
Membranes with different service lives (420 years) tested for leaching of PFAS and TOF
Membranes produced before 2022
Not relevant in 2022 considering a life-time of 10 years
Either incinerated or disposed of in nonhazardous landfills
WWTP & Sewage sludge
Disposal of membranes at the end of service life described in row below
Membranes are stable and leaching tests indicated no directly related PFAS or TOF concentrations above detection limit and/or background concentration
Incineration: No data is currently available but R&D activities on PVDF incineration are on going.
Landfills: Membranes are considered to be stable. Anaerobic degradation tests did not provide evidence of degradation; PFAS in supernatant and solids were lower or in range of control values
No PFAS and no TOF detected above detection limit and/or background concentration; however, other TOF measurements showed leaching of raw material which may end up in wastewater and sewage sludge
Membranes are stable and leaching tests indicated no directly related PFAS or TOF concentrations above detection limit and/or background concentration
Reference
Section 3.1 Sections 3 and 4.3.3 Sections 4.2.4, 4.4.1, and 4.4.2
Section 4.2.3
Section 4.3.4
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PVDF Life-cycle step
Tonnage PVDF (in 2022)
Percentage of total ordered PVDF in 2022
Disposal route
PFAS emission?
Reference
Disposed PVDF
t1)
membranes in EEA
Membranes produced before 2022
Either incinerated or disposed of in nonhazardous landfills2)
Incineration: No data is currently available but R&D activities on PVDF incineration are on going.
Sections 4.2.4, 4.4.1 and 4.4.2
Landfills: Membranes are considered to be stable. Anaerobic degradation tests did not provide evidence of degradation; PFAS in supernatant and solids were lower or in range of control values
1) Based on commercialized PVDF within the EEA while considering a membrane lifetime of 10 years, i.e .this number represents the total tonnage of PVDF commercialized in 2012 within the EEA. 2) 45% of commercialized PVDF is disposed of in non-hazardous landfill and 55% is disposed via incineration based on a downstream user survey.
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6 REFERENCES
Aleksandrov, K., Gehrmann, H.-J., Hauser, M., Mtzing, H., Pigeon, D., Stapf, D., Wexler, M., 2019. Waste incineration of Polytetrafluoroethylene (PTFE) to evaluate potential formation of per- and Poly-Fluorinated Alkyl Substances (PFAS) in flue gas. Chemosphere 226, 898-906. https://doi.org/10.1016/j.chemosphere.2019.03.191
Danz, P., Aryan, V., Mhle, E., Nowara, N., 2019. Experimental study on fluorine release from photovoltaic backsheet materials containing PVF and PVDF during pyrolysis and incineration in a technical lab-scale reactor at various temperatures. Toxics 7, 47.
ECHA, 2012. Guidance on information requirements and chemical safety assessment Chapter R.18: Exposure scenario building and environmental release estimation for the waste life stage (Ver. 2.1).
ECHA, BAuA, RIVM, KEMI, Norwegian Environment Agency, The Danish Environmental Protection Agency, 2023. Annex B to the Annex XV restriction report - Proposal for a restriction: Per- and polyfluoroalkyl substances (PFASs) - Version number 2.
European Commission - Joint Research Centre (JRC) Institute for Health and Consumer Protection (IHCP), 2002. Guidance Document on the Determination of Particle Size Distribution, Fibre Length and Diameter Distribution of Chemical Substances (EUR 20268 EN).
Korzeniowski, S.H., Buck, R.C., Newkold, R.M., kassmi, A.E., Laganis, E., Matsuoka, Y., Dinelli, B., Beauchet, S., Adamsky, F., Weilandt, K., Soni, V.K., Kapoor, D., Gunasekar, P., Malvasi, M., Brinati, G., Musio, S., 2023. A critical review of the application of polymer of low concern regulatory criteria to fluoropolymers II: Fluoroplastics and fluoroelastomers. Integrated Environmental Assessment and Management 19, 326-354. https://doi.org/10.1002/ieam.4646
Marshall, J.E., Zhenova, A., Roberts, S., Petchey, T., Zhu, P., Dancer, C.E.J., McElroy, C.R., Kendrick, E., Goodship, V., 2021. On the Solubility and Stability of Polyvinylidene Fluoride. Polymers (Basel) 13. https://doi.org/10.3390/polym13091354
NCBI, 2023. NCBI. PubChem Compound Summary for CID 6369, Vinylidene fluoride.
Rabuni, M.F., Nik Sulaiman, N.M., Aroua, M.K., Hashim, N.A., 2013. Effects of Alkaline Environments at Mild Conditions on the Stability of PVDF Membrane: An Experimental Study. Ind. Eng. Chem. Res. 52, 15874-15882. https://doi.org/10.1021/ie402684b
Silva, A.J. de J., Contreras, M.M., Nascimento, C.R., Costa, M.F. da, 2020. Kinetics of thermal degradation and lifetime study of poly(vinylidene fluoride) (PVDF) subjected to bioethanol fuel accelerated aging. Heliyon 6, e04573. https://doi.org/10.1016/j.heliyon.2020.e04573
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Annex 6
CHEMICAL SAFETY REPORT
6 The annex is only available in the confidential version of this document and was removed from the public version.
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